The 8 Best Moments of NASA's MESSENGER

After a decade of groundbreaking research, NASA's probe MESSENGER will finish its mission in 2015. It will do one last thruster boost on January 21, at which time it is expected to take shots of Mercury's surface in unprecedented detail before its orbit decays and it crashes into the hot, heavily cratered planet. In honor of its impending demise, here are some of the greatest MESSENGER moments from the last decade:

MESSENGER enters Mercury's orbit

[Credit: NASA]

MESSENGER became the first spacecraft to orbit Mercury on March 18, 2011. It achieved a near-perfect orbit, coming within 200 km and up to 15,000 km away from the surface every twelve hours in order to protect it from the heat emanating from Mercury's surface. The above picture is the first-ever photograph taken from Mercury's orbit.

Earth flyby

MESSENGER did a flyby of Earth one year after launch, in August 2005, with the closest approach at an altitude of 2,347 km.

Venus flybys

[Credit: NASA]

Two flybys of Venus occurred in 2006 and 2007, respectively. The first flyby was conducted during a period in which the Sun inhibited radio contact with Earth, so no scientific observation occurred and a second flyby was planned. The second flyby allowed for the imaging of the upper atmosphere, as well as observation of its composition.

MESSENGER images ISON and Encke

[Credit: NASA]

MESSENGER took images of comets ISON and Encke at their closest approach to Mercury. The latter, shown above, occurred on November 17, 2013, while the below image of ISON was taken on November 20.

[Credit: NASA]

100% coverage of Mercury's surface

[Credit: NASA]

At the tail end of 2012, MESSENGER finally collected enough images to create a mosaic of the planet's entire surface.

10th anniversary video

In honor of the tenth anniversary of Messenger's expedition, NASA released this video from early in the mission of a close-up flyover of Mercury. "This view is what a traveler on the MESSENGER spacecraft might see during low-altitude operations in the coming year," said Messenger co-investigator Scott Murchie of APL. "During the final phase of its mission, MESSENGER's science instruments will use low-altitude operations like this to explore the surface and subsurface of Mercury at unprecedented resolution."

The first solar day on Mercury in spectral variations

[Credit: NASA]

This image shows a composite of data from the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), which collects spectra at ultraviolet to near-infrared wavelengths, and corresponding images from MESSENGER on the first solar day on Mercury. The blue/purple/pink areas indicates places where ultraviolet variations correlate with geological features.

MESSENGER finds a smiley face on Mercury's surface

[Credit: NASA]

MESSENGER imaged this crater, which NASA cheekily called the "Happy Little Crater," in 2013. NASA stated that "the central peaks of this complex crater have formed in such a way that it resembles a smiling face."